The objectives of this project are: 1. to investigate the activation/detoxification pathways of a series of polycyclicaromatic hydrocarbons (PAH) by a comparative metabolism study. 2. to evaluate the "Bay Region" hypothesis. In vivo and in vitro metabolites of methyl- and fluoro-derivatives of benz(a)anthracene will be examined in Sprague-Dawley rats in order to determine how these structural parameters influence the biotransformation of these compounds. In addition, the effect of these parameters on the reactivities of potentially active metabolites will be investigated by studying the reactions between these metabolites and nucleophiles.